Autonomic, Behavioral, and Subjective Pain Responses in Alzheimer's Disease.

OBJECTIVE: To compare autonomic, behavioral, and subjective pain responses of patients with Alzheimer's disease (AD) to those of healthy seniors (HS). As few studies have examined patients with severe Alzheimer's disease (sAD), we emphasized inclusion of these patients together with mild/moderate Alzheimer's disease (mAD) patients to characterize pain responses potentially affected by disease severity. DESIGN: A controlled cross-sectional study involving repeated measures behavioral pain testing. SETTING: An outpatient clinical setting and local nursing facilities. SUBJECTS: Community dwelling HS controls (N = 33) and individuals with chart-confirmed diagnoses of AD (N = 38, Diagnostic and Statistical Manual-IV criteria). METHODS: HS and AD groups were compared in their responses to repeated applications of five pressure intensities (1-5 kg) on the distal forearm. Autonomic responses (heart rate [HR]), pain behaviors (vocal, facial, and bodily as scored by the Pain Assessment in Advanced Dementia [PAINAD] scale), and subjective pain ratings (Faces Pain Scale-Revised) were measured. RESULTS: HR responses to pressure stimuli were differentially affected based on AD severity: sAD patients had generally decreased HR reactivity compared with other groups (P < 0.01). In contrast, pain behaviors were increased in AD regardless of severity (P < 0.001), compared with HS, for all but the lowest pressure intensity. Increased behaviors occurred in all measured domains of the PAINAD (P < 0.005). While sAD were unreliable subjective reporters, mAD patients (N = 17) rated low level pressures as more painful than HS (P < 0.01). CONCLUSION: These findings provide behavioral and subjective-report evidence of increased acute pain sensitivity in AD, which should be taken into consideration with respect to pain management across the spectrum of AD severity.

Keeping Calm and Carrying On: Relating Affect Spin and Pulse to Complex Skill Acquisition and Adaptive Performance.

The purpose of this laboratory study involving repeated measures of emotion as 214 undergraduates (58.4% male) learned a complex video game was to address the need for empirical research on dynamic personality constructs by examining how two aspects of affect variability-spin and pulse-explain variance in skill acquisition and adaptive performance. Spin refers to within-person fluctuations in affect pleasantness and activation potential. Pulse refers to within-person fluctuations in affect intensity. Despite research showing high affect variability reflects a personality profile of heighted reactivity to emotionally charged events and poor adjustment, little empirical research has examined their relationships with behavioral outcomes, much less aspects of skilled performance. Compared to traditional measures of personality, which yield weak effects for predicting acquisition and adaptive performance, measures of affect variability hold considerable promise because they, like performance, reflect dynamic within-person phenomena. Accordingly, the main question addressed by this study was whether spin and pulse incrementally explain acquisition and adaptive performance beyond Big Five measures of personality. In general, we expected harmful, incremental effects for both spin and pulse, and hypothesized two mechanisms for these harmful effects: (1) by undermining effort and (2) by undermining the effort-performance relationship. Using a task-change paradigm and discontinuous growth modeling that disentangled adaptation from acquisition, results showed that affect variability, independent of the Big Five, produced harmful effects via both hypothesized mechanisms. Participants higher in affect spin and pulse showed less sustained effort across performance sessions and exhibited lower performance. Furthermore, the harmful effects of spin and pulse were stronger in adaptation compared to acquisition, with pulse showing stronger direct effects on performance during adaptation and spin moderating the effort-performance relationship such that effort was only beneficial during adaptation for those lower in spin. In light of these results, one might question the common advice "keep calm and carry on," which may not be viable for persons high in affect variability. Accordingly, results are discussed in terms of the need to better understand the specific mediating processes by which high affect variability undermines success across a variety of learning and performance contexts.

Altered Behavioral and Autonomic Pain Responses in Alzheimer's Disease Are Associated with Dysfunctional Affective, Self-Reflective and Salience Network Resting-State Connectivity.

While pain behaviors are increased in Alzheimer's disease (AD) patients compared to healthy seniors (HS) across multiple disease stages, autonomic responses are reduced with advancing AD. To better understand the neural mechanisms underlying these phenomena, we undertook a controlled cross-sectional study examining behavioral (Pain Assessment in Advanced Dementia, PAINAD scores) and autonomic (heart rate, HR) pain responses in 24 HS and 20 AD subjects using acute pressure stimuli. Resting-state fMRI was utilized to investigate how group connectivity differences were related to altered pain responses. Pain behaviors (slope of PAINAD score change and mean PAINAD score) were increased in patients vs. CONTROLS: Autonomic measures (HR change intercept and mean HR change) were reduced in severe vs. mildly affected AD patients. Group functional connectivity differences associated with greater pain behavior reactivity in patients included: connectivity within a temporal limbic network (TLN) and between the TLN and ventromedial prefrontal cortex (vmPFC); between default mode network (DMN) subcomponents; between the DMN and ventral salience network (vSN). Reduced HR responses within the AD group were associated with connectivity changes within the DMN and vSN-specifically the precuneus and vmPFC. Discriminant classification indicated HR-related connectivity within the vSN to the vmPFC best distinguished AD severity. Thus, altered behavioral and autonomic pain responses in AD reflects dysfunction of networks and structures subserving affective, self-reflective, salience and autonomic regulation.

Effects of Alzheimer Disease on the Facial Expression of Pain.

OBJECTIVES: Facial expression may be a surrogate marker of pain in Alzheimer disease (AD) when self-report of pain is compromised. Recent studies have demonstrated increased pain sensitivity in AD; however, experimental pain studies analyzing facial expressions in AD are limited and report inconsistent results. The aims of this study were to examine facial expression of pain in AD patients and its relationship to sum-scored measures of multiple pain behavioral domains and subjective pain ratings. MATERIALS AND METHODS: The Facial Action Coding System (FACS) was used to characterize facial expressions in 35 AD patients and 33 healthy seniors during pressure algometry. To improve pain specificity, facial responses were categorized as pain-relevant or pain-irrelevant before group analyses. We also assessed the relationship of AD severity to differential facial responsiveness by correlating FACS-based results with clinical pain scales (portions of the Pain Assessment in Advanced Dementia scale and the Faces Pain Scale-Revised [FPS-R]). RESULTS: No significant relationship was found between AD severity and FACS scores. Pain-relevant, but not irrelevant, FACS scores were increased in AD patients compared with seniors without AD. Pain Assessment in Advanced Dementia scale stimulus-response slopes were correlated with those of pain-relevant FACS and FPS-R in both the groups. Pain-relevant FACS slopes showed no relationship with those of the FPS-R in either group. DISCUSSION: Pain sensitivity is increased across all severities of AD when measured using the FACS. Clinical observational pain scales support the relevance of facial expression as a partial compensatory pain communication modality for AD. However, measures of pain behavior that sum across objective coding of several domains provide a better indicator of subjective pain than measures of facial expression alone.